<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, sans-serif;
      color: #1e2945;
      background: #ffffff;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
      user-select: none;
    }
    
    /* Navigation / Step Buttons */
    .controls {
      display: flex;
      justify-content: center;
      align-items: center;
      gap: 8px;
    }
    .btn-step {
      background: #f1f5f9;
      border: 2px solid transparent;
      color: #1e2945;
      padding: 6px 14px;
      border-radius: 20px;
      font-size: 13px;
      font-weight: 700;
      cursor: pointer;
      transition: all 0.2s ease;
    }
    .btn-step.active {
      background: #eff6ff;
      border-color: #2563eb;
      color: #2563eb;
    }
    .btn-play {
      background: #2563eb;
      border: none;
      color: #fff;
      width: 32px;
      height: 32px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      font-size: 12px;
    }

    /* Main Display Grid */
    .stage-container {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      align-items: stretch;
    }
    @media (max-width: 480px) {
      .stage-container {
        grid-template-columns: 1fr;
      }
    }

    /* Card Panels */
    .panel {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
    }
    .panel-title {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      margin-bottom: 6px;
      display: flex;
      align-items: center;
      gap: 6px;
    }

    /* Collision Box */
    .collision-box {
      width: 100%;
      height: 180px;
      background: #ffffff;
      border: 1.5px solid #cbd5e1;
      border-radius: 8px;
      position: relative;
      overflow: hidden;
    }
    
    .particle {
      position: absolute;
      width: 14px;
      height: 14px;
      border-radius: 50%;
      transform: translate(-50%, -50%);
      transition: all 0.4s ease;
    }
    .particle.reactant-a { background: #2563eb; }
    .particle.reactant-b { background: #f43f5e; }
    .particle.product { background: #9333ea; }

    .collision-star {
      position: absolute;
      color: #eab308;
      font-size: 20px;
      transform: translate(-50%, -50%);
      pointer-events: none;
      animation: pulse 1s infinite alternate ease-in-out;
    }
    @keyframes pulse {
      0% { transform: translate(-50%, -50%) scale(0.85); opacity: 0.8; }
      100% { transform: translate(-50%, -50%) scale(1.2); opacity: 1; }
    }

    /* Legend */
    .legend {
      display: flex;
      justify-content: center;
      gap: 12px;
      margin-top: 6px;
      font-size: 11px;
      font-weight: 600;
    }
    .legend-item {
      display: flex;
      align-items: center;
      gap: 4px;
    }
    .dot-sample {
      width: 9px;
      height: 9px;
      border-radius: 50%;
    }

    /* Rate Graph */
    .graph-box {
      width: 100%;
      height: 180px;
      display: flex;
      align-items: center;
      justify-content: center;
    }
    svg {
      width: 100%;
      height: 100%;
    }
    .axis { stroke: #94a3b8; stroke-width: 1.5; stroke-linecap: round; }
    .axis-label { font-size: 10px; fill: #64748b; font-weight: 600; }
    .curve { fill: none; stroke: #cbd5e1; stroke-width: 2.5; stroke-linecap: round; }
    .curve-active { fill: none; stroke: #2563eb; stroke-width: 3; stroke-linecap: round; }
    .tangent-line { stroke: #f43f5e; stroke-width: 2.5; stroke-dasharray: 4 3; }
    .point-dot { fill: #f43f5e; stroke: #ffffff; stroke-width: 2; }
    
    /* Rate Status Badge */
    .status-banner {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 6px 12px;
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      text-align: center;
      display: flex;
      justify-content: space-around;
      align-items: center;
    }
    .status-highlight {
      color: #2563eb;
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="btn-step active" id="btn0" onclick="setStage(0)">1. Start</button>
    <button class="btn-step" id="btn1" onclick="setStage(1)">2. Middle</button>
    <button class="btn-step" id="btn2" onclick="setStage(2)">3. End</button>
    <button class="btn-play" id="playBtn" onclick="togglePlay()">⏸</button>
  </div>

  
  <div class="stage-container">
    
    <div class="panel">
      <div class="panel-title">Molecules & Collisions</div>
      <div class="collision-box" id="collisionBox"></div>
      <div class="legend">
        <div class="legend-item"><span class="dot-sample" style="background:#2563eb"></span>Reactant</div>
        <div class="legend-item"><span class="dot-sample" style="background:#f43f5e"></span>Reactant</div>
        <div class="legend-item"><span class="dot-sample" style="background:#9333ea"></span>Product</div>
      </div>
    </div>

    
    <div class="panel">
      <div class="panel-title">Rate Curve & Tangent</div>
      <div class="graph-box">
        <svg viewBox="0 0 240 180" id="rateSvg">
          
          <line x1="36" y1="150" x2="225" y2="150" class="axis" />
          <line x1="36" y1="150" x2="36" y2="18" class="axis" />
          
          
          <text x="220" y="166" class="axis-label" text-anchor="end">Time</text>
          <text x="14" y="24" class="axis-label" transform="rotate(-90 14,24)" text-anchor="end">Product</text>

          
          <path id="baseCurve" class="curve" d="" />
          <path id="activeCurve" class="curve-active" d="" />

          
          <line id="tangentLine" class="tangent-line" x1="0" y1="0" x2="0" y2="0" />
          <circle id="curvePoint" class="point-dot" cx="0" cy="0" r="4.5" />
        </svg>
      </div>
    </div>
  </div>

  
  <div class="status-banner">
    <div>Collisions: <span class="status-highlight" id="lblCollisions">Rapid & Frequent</span></div>
    <div>Slope: <span class="status-highlight" id="lblSlope">Steep Tangent</span></div>
    <div>Rate: <span class="status-highlight" id="lblRate">Fastest</span></div>
  </div>

  <script>
    // Exact mathematical curve generation
    function calcY(x) {
      return 150 - 128 * (1 - Math.exp(-(x - 36) / 42));
    }

    const startX = 36;
    const endX = 220;
    let pathD = `M ${startX} 150`;
    for (let x = startX; x <= endX; x += 2) {
      pathD += ` L ${x} ${calcY(x).toFixed(2)}`;
    }
    document.getElementById('baseCurve').setAttribute('d', pathD);

    const stages = [
      {
        name: 'Start',
        x: 48,
        tLen: 28,
        collisions: 'Frequent',
        slope: 'Steep Tangent',
        rate: 'Fastest',
        stars: [
          { top: '35%', left: '38%' },
          { top: '65%', left: '60%' },
          { top: '30%', left: '75%' }
        ],
        particles: [
          // All reactants (Blue & Coral)
          { t: '25%', l: '20%', type: 'reactant-a' },
          { t: '40%', l: '32%', type: 'reactant-b' },
          { t: '75%', l: '22%', type: 'reactant-a' },
          { t: '60%', l: '52%', type: 'reactant-b' },
          { t: '72%', l: '66%', type: 'reactant-a' },
          { t: '25%', l: '68%', type: 'reactant-b' },
          { t: '38%', l: '82%', type: 'reactant-a' },
          { t: '80%', l: '85%', type: 'reactant-b' },
          { t: '20%', l: '48%', type: 'reactant-a' },
          { t: '55%', l: '15%', type: 'reactant-b' }
        ]
      },
      {
        name: 'Middle',
        x: 105,
        tLen: 38,
        collisions: 'Fewer',
        slope: 'Gentle Slope',
        rate: 'Slowing Down',
        stars: [
          { top: '48%', left: '50%' }
        ],
        particles: [
          // Mostly purple products + few reactants
          { t: '25%', l: '20%', type: 'product' },
          { t: '45%', l: '44%', type: 'reactant-a' },
          { t: '52%', l: '56%', type: 'reactant-b' },
          { t: '75%', l: '22%', type: 'product' },
          { t: '68%', l: '70%', type: 'product' },
          { t: '25%', l: '68%', type: 'product' },
          { t: '38%', l: '82%', type: 'product' },
          { t: '80%', l: '85%', type: 'product' },
          { t: '20%', l: '48%', type: 'product' },
          { t: '55%', l: '15%', type: 'product' }
        ]
      },
      {
        name: 'End',
        x: 185,
        tLen: 42,
        collisions: 'Zero (None)',
        slope: 'Flat (Slope = 0)',
        rate: 'Reaction Stopped',
        stars: [],
        particles: [
          // 100% Purple Products
          { t: '25%', l: '20%', type: 'product' },
          { t: '40%', l: '35%', type: 'product' },
          { t: '75%', l: '22%', type: 'product' },
          { t: '58%', l: '50%', type: 'product' },
          { t: '72%', l: '66%', type: 'product' },
          { t: '25%', l: '68%', type: 'product' },
          { t: '38%', l: '82%', type: 'product' },
          { t: '80%', l: '85%', type: 'product' },
          { t: '20%', l: '48%', type: 'product' },
          { t: '55%', l: '15%', type: 'product' }
        ]
      }
    ];

    let currentStage = 0;
    let timer = null;
    let isPlaying = true;

    function renderStage(idx) {
      const s = stages[idx];

      // Update buttons
      for (let i = 0; i < 3; i++) {
        document.getElementById(`btn${i}`).classList.toggle('active', i === idx);
      }

      // Update Collision Box
      const box = document.getElementById('collisionBox');
      box.innerHTML = '';
      
      // Starbursts
      s.stars.forEach(st => {
        const star = document.createElement('div');
        star.className = 'collision-star';
        star.style.top = st.top;
        star.style.left = st.left;
        star.innerHTML = '✦';
        box.appendChild(star);
      });

      // Particles
      s.particles.forEach(p => {
        const dot = document.createElement('div');
        dot.className = `particle ${p.type}`;
        dot.style.top = p.t;
        dot.style.left = p.l;
        box.appendChild(dot);
      });

      // Update Active Curve Path up to x
      let actD = `M ${startX} 150`;
      for (let x = startX; x <= s.x; x += 2) {
        actD += ` L ${x} ${calcY(x).toFixed(2)}`;
      }
      document.getElementById('activeCurve').setAttribute('d', actD);

      // Tangent Line Calculation: derivative dy/dx
      const curY = calcY(s.x);
      // derivative of 150 - 128*(1 - exp(-(x-36)/42)) is -(128/42)*exp(-(x-36)/42)
      const slope = (idx === 2) ? 0 : -(128 / 42) * Math.exp(-(s.x - 36) / 42);
      
      const dx = s.tLen;
      const dy = slope * dx;

      const tLine = document.getElementById('tangentLine');
      tLine.setAttribute('x1', (s.x - dx).toFixed(1));
      tLine.setAttribute('y1', (curY - dy).toFixed(1));
      tLine.setAttribute('x2', (s.x + dx).toFixed(1));
      tLine.setAttribute('y2', (curY + dy).toFixed(1));

      const pt = document.getElementById('curvePoint');
      pt.setAttribute('cx', s.x);
      pt.setAttribute('cy', curY.toFixed(1));

      // Labels
      document.getElementById('lblCollisions').textContent = s.collisions;
      document.getElementById('lblSlope').textContent = s.slope;
      document.getElementById('lblRate').textContent = s.rate;
    }

    function setStage(idx) {
      currentStage = idx;
      renderStage(currentStage);
    }

    function nextStage() {
      currentStage = (currentStage + 1) % stages.length;
      renderStage(currentStage);
    }

    function startAutoPlay() {
      if (timer) clearInterval(timer);
      timer = setInterval(nextStage, 3200);
      isPlaying = true;
      document.getElementById('playBtn').textContent = '⏸';
    }

    function stopAutoPlay() {
      if (timer) clearInterval(timer);
      isPlaying = false;
      document.getElementById('playBtn').textContent = '▶';
    }

    function togglePlay() {
      if (isPlaying) stopAutoPlay();
      else {
        nextStage();
        startAutoPlay();
      }
    }

    // Initialize
    renderStage(0);
    startAutoPlay();
  </script>
</body>
</html>

Interpreting Reaction Rate Graphs

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #f8fafc;
      color: #1e293b;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    /* Stage Selector Tabs */
    .controls {
      display: flex;
      gap: 6px;
      justify-content: center;
      flex-wrap: wrap;
    }
    .step-btn {
      background: #ffffff;
      border: 1.5px solid #e2e8f0;
      padding: 6px 12px;
      border-radius: 8px;
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
      transition: all 0.25s ease;
    }
    .step-btn.active {
      background: #0f172a;
      color: #ffffff;
      border-color: #0f172a;
    }
    .step-num {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 18px;
      height: 18px;
      border-radius: 50%;
      background: rgba(0,0,0,0.08);
      font-size: 11px;
    }
    .step-btn.active .step-num {
      background: rgba(255,255,255,0.25);
    }

    /* Side-by-side Graph Grid */
    .graphs-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
    }
    @media (max-width: 520px) {
      .graphs-grid {
        grid-template-columns: 1fr;
      }
    }

    .graph-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 8px 4px 8px;
      display: flex;
      flex-direction: column;
    }
    .graph-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 4px;
      padding: 0 4px;
    }
    .graph-title {
      font-size: 13px;
      font-weight: 700;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .badge-product {
      color: #0891b2;
      background: #ecfeff;
      border: 1px solid #a5f3fc;
      border-radius: 4px;
      padding: 2px 6px;
      font-size: 11px;
    }
    .badge-reactant {
      color: #c2410c;
      background: #fff7ed;
      border: 1px solid #ffedd5;
      border-radius: 4px;
      padding: 2px 6px;
      font-size: 11px;
    }

    svg {
      width: 100%;
      height: auto;
      display: block;
    }

    .axis-line { stroke: #94a3b8; stroke-width: 1.5; stroke-linecap: round; }
    .grid-line { stroke: #f1f5f9; stroke-width: 1; }
    .plateau-line { stroke: #cbd5e1; stroke-dasharray: 4 3; stroke-width: 1.5; }
    .axis-label { font-size: 9.5px; fill: #64748b; font-weight: 600; }
    .tick-label { font-size: 8.5px; fill: #94a3b8; }
    .plateau-label { font-size: 8.5px; font-weight: 600; fill: #64748b; }

    /* Curve paths */
    .curve-product {
      fill: none;
      stroke: #06b6d4;
      stroke-width: 2.75;
      stroke-linecap: round;
    }
    .curve-reactant {
      fill: none;
      stroke: #f97316;
      stroke-width: 2.75;
      stroke-linecap: round;
    }

    /* Interactive Tangents and Highlights */
    .tangent-line {
      stroke-width: 1.75;
      stroke-linecap: round;
      transition: opacity 0.3s ease;
    }
    .tangent-prod { stroke: #0284c7; }
    .tangent-react { stroke: #dc2626; }
    .stage-point {
      transition: transform 0.25s ease, r 0.25s ease, opacity 0.3s ease;
      cursor: pointer;
    }

    .stage-group {
      opacity: 0.2;
      transition: opacity 0.3s ease;
    }
    .stage-group.active {
      opacity: 1;
    }

    /* Unified Bottom Summary Card */
    .summary-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px 14px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
    }
    .summary-left {
      display: flex;
      align-items: center;
      gap: 10px;
    }
    .summary-icon {
      font-size: 20px;
      line-height: 1;
    }
    .summary-main {
      font-size: 13px;
      font-weight: 700;
      color: #0f172a;
    }
    .summary-sub {
      font-size: 12px;
      color: #64748b;
      margin-top: 1px;
    }
    .gradient-badge {
      font-size: 12px;
      font-weight: 700;
      padding: 4px 10px;
      border-radius: 6px;
      white-space: nowrap;
    }
    .grad-steep { background: #dbeafe; color: #1d4ed8; }
    .grad-gentle { background: #fef3c7; color: #b45309; }
    .grad-zero { background: #f1f5f9; color: #475569; }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="step-btn active" data-step="0">
      <span class="step-num">1</span> Start: Fastest
    </button>
    <button class="step-btn" data-step="1">
      <span class="step-num">2</span> Middle: Slowing
    </button>
    <button class="step-btn" data-step="2">
      <span class="step-num">3</span> End: Stopped
    </button>
  </div>

  
  <div class="graphs-grid">
    
    
    <div class="graph-card">
      <div class="graph-header">
        <span class="graph-title">Product Formed</span>
        <span class="badge-product">Gas Volume / cm³</span>
      </div>
      <svg viewBox="0 0 280 185">
        
        <line class="grid-line" x1="42" y1="145" x2="265" y2="145" />
        <line class="grid-line" x1="42" y1="105" x2="265" y2="105" />
        <line class="grid-line" x1="42" y1="65"  x2="265" y2="65" />
        <line class="grid-line" x1="42" y1="35"  x2="265" y2="35" />
        
        
        <line class="plateau-line" x1="42" y1="35" x2="265" y2="35" />
        <text class="plateau-label" x="145" y="30" text-anchor="middle">Max Product (Reaction Complete)</text>

        
        <line class="axis-line" x1="42" y1="145" x2="268" y2="145" />
        <line class="axis-line" x1="42" y1="145" x2="42" y2="18" />

        
        <text class="axis-label" x="265" y="160" text-anchor="end">Time (s) →</text>
        <text class="axis-label" x="14" y="24" transform="rotate(-90 14,24)" text-anchor="end">Volume (cm³) →</text>
        <text class="tick-label" x="35" y="148" text-anchor="end">0</text>

        
        <path class="curve-product" d="M 42 145 C 55 75, 95 38, 175 35 L 265 35" />

        
        <g class="stage-group active" id="prod-stage-0">
          <line class="tangent-line tangent-prod" x1="32" y1="160" x2="85" y2="65" stroke-dasharray="3 2" />
          <circle class="stage-point" cx="42" cy="145" r="4.5" fill="#0284c7" stroke="#ffffff" stroke-width="1.5" />
          <polygon points="42,145 78,145 78,78" fill="rgba(2,132,199,0.12)" stroke="#0284c7" stroke-width="0.8" />
          <text x="86" y="85" font-size="9" font-weight="700" fill="#0284c7">Steep tangent</text>
        </g>

        
        <g class="stage-group" id="prod-stage-1">
          <line class="tangent-line tangent-prod" x1="60" y1="88" x2="145" y2="40" stroke-dasharray="3 2" />
          <circle class="stage-point" cx="95" cy="58" r="4.5" fill="#0284c7" stroke="#ffffff" stroke-width="1.5" />
          <polygon points="75,70 120,70 120,48" fill="rgba(2,132,199,0.12)" stroke="#0284c7" stroke-width="0.8" />
          <text x="126" y="60" font-size="9" font-weight="700" fill="#0284c7">Gentle slope</text>
        </g>

        
        <g class="stage-group" id="prod-stage-2">
          <line class="tangent-line tangent-prod" x1="170" y1="35" x2="255" y2="35" stroke-width="2.5" />
          <circle class="stage-point" cx="210" cy="35" r="4.5" fill="#0284c7" stroke="#ffffff" stroke-width="1.5" />
          <text x="210" y="50" font-size="9" font-weight="700" fill="#0284c7" text-anchor="middle">Gradient = 0</text>
        </g>
      </svg>
    </div>

    
    <div class="graph-card">
      <div class="graph-header">
        <span class="graph-title">Reactant Remaining</span>
        <span class="badge-reactant">Flask Mass / g</span>
      </div>
      <svg viewBox="0 0 280 185">
        
        <line class="grid-line" x1="42" y1="145" x2="265" y2="145" />
        <line class="grid-line" x1="42" y1="115" x2="265" y2="115" />
        <line class="grid-line" x1="42" y1="75"  x2="265" y2="75" />
        <line class="grid-line" x1="42" y1="35"  x2="265" y2="35" />

        
        <line class="plateau-line" x1="42" y1="115" x2="265" y2="115" />
        <text class="plateau-label" x="145" y="110" text-anchor="middle">Final Mass (Gas Escaped)</text>

        
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Plotting Rate of Reaction Graphs from Raw Experimental Data

Determining Mean Rates from Graphs over Specific Time Intervals

Drawing Tangents to Determine Rates on Curved Graphs

Calculating Instantaneous Rates from Tangent Gradients

Plotting and Interpreting Rate Graphs: Tangents and Initial Rates

Interpreting How Reactant Depletion Affects Graph Gradient and Curve Plateaus

science

Graphing Reaction Rates and Gradient Analysis

Interpreting Rate Data from Experiments

Mathematical Relationships: Direct Proportionality Between Concentration and Rate

Calculating Rate Ratios and Scaling Factors for Surface Area and Pressure

Comparing Rate Changes with Temperature: The Rule of Thumb and Exponential Trends

Mathematical Comparison of Catalysed versus Uncatalysed Reactions

Working Scientifically: Calculating Reaction Rate Uncertainties and Percentage Errors

GCSE Exam Mastery: Multi-Step Mathematical Calculations in Reaction Rates

Proportionality and Rate Factor Mathematics

UK-GCSE-SCIENCE-CHEM-RC-03-02

UK-GCSE-SCIENCE-CHEM-RC-03-02

Aligned learning resources

Related diagrams